Stranded rope and process for making it



Gd. 1, 1968 v. s. VAN scoY 3,403,503

STRANDED ROPE AND PROCESS FOR MAKING IT Filed June 30, 1967 F I G I [-16.2

IULTIFILAIENT mu m sum FIBERS SINGLES msmc Y PROCESS or aucnm mm 669,197

THREE-FLY msnnc non cono WRAPPED mu smuo roams smno Foams ROPE smno ROPE srmn ROPE umc ROPE ums ROPE ROPE INVENTOR VICTOR SAIUEL V 800' ATTORNEY United States Patent O 3,403,503 STRANDED ROPE AND PROCESS FOR MAKING IT Victor Samuel Van Scoy, Newark, Del., assignor to E. I.

du Pont de Nemours and Company, Wilmington, Del.,

a corporation of Delaware Filed June 30, 1967, Ser. No. 650,438 8 Claims. (Cl. 57-144) ABSTRACT OF THE DHSCLOSURE A stranded rope structure and a process for making the rope which comprises twisting in one direction a plurality of zero twist wrapped yarns to form a rope strand and then twisting a plurality of said rope strands in an opposite direction to form the rope; said wrapped yarn being characterized as comprising a core composed of at least two continuous integral core elements of bundles of continuous filament textile fibers and surface wrappings composed of textile fiber staple, the surface fibers being tightly twisted about the core with portions of fibers locked into place in the core with the core fibers being relatively straight and held together as a compact bundle by the surface wrappings, said yarn having from 2% to about 20% by weight of staple fiber wrapping and having a twist differential between continuous core elements and said wrappings within the range of about 2 to about 20 turns per inch.

BACKGROUND OF THE INVENTION (1) Field of the inventin.This invention relates to improvements in the manufacture of ply-twisted structures, and more particularly to an improved method for making ropes and cordage which results in products having properties superior to those available in the past.

(2) Description of the prior art.Conventionally, ropes are manufactured of balanced ply yarn construction using four steps; namely, singles twisting to form a rope yarn, three-ply twisting rope yarns to form a rope cord, strand forming, and rope laying. The conventional method of making balanced plied ropes is described in more detail by Himmelfarb et al. in US. Patent 2,971,- 321, dated Oct. 16, 1956.

Wrapped yarns of the type useful in practicing the present invention are disclosed in Belgian Patent 669,797, granted Sept. 30, 1965. The wrapped yarn disclosed in the Belgian patent comprises a core composed of at least two continuous integral core elements of textile fibers and surface wrappings composed of discontinuous textile fibers, the surface fibers being tightly twisted about the core with portions of fibers locked in place in the core, and the core fibers being relatively straight and held to gether as a compact bundle by the surf-ace wrappings.

SUMMARY OF THE INVENTION The present invention provides a new rope construction having the desirable combination of higher breaking strength per unit of weight, lower working elongation, superior hand and appearance, and improved frictional characteristics as compared with conventional rope constructions of the prior art. This invention further provides rope, cordage, and similar plied structures by an improved and more economical process. Another provision of the invention is to reduce the number of manufacturing steps in rope making. Additional advantages of the invention will appear from the discussion of the invention that follows.

The invention comprehends an improved process for manufacturing ply-twisted structures comprising the steps of (1) providing a wrapped yarn comprising a core com- 3,403,503 Patented Oct. 1, 1968 ice posed of at least two continuous core elements which are substantially free of twist and surface wrappings of discontinuous textile fibers tightly twisted about the core with portions of fibers locked into place in the core and having a true twist differential between core and surface wrappings of at least an average of two turns per inch, (2) forming a rope strand by twisting a multiplicity of the wrapped yarns to produce a twisted product, and (3) twisting together a plurality of rope strands in a direction opposed to the direction of twist in said strand product to produce an improved rope.

The invention will be better understood by reference to the accompanying drawings.

FIGURE 1 is a flow sheet of a conventional process for manufacturing rope, and

FIGURE 2 is a flow sheet showing the improved process of this invention for manufacturing rope.

The yarn for use in this process is a relatively new wrapped yam structure. This yarn may be described as a wrapped yarn comprising a core composed of at least two continuous integral core elements of textile fibers and surface wrappings composed of discontinuous textile fibers, the surface fibers being tightly twisted about the core with portions of fibers locked into place in the core, the core fibers being relatively straight and held together as a compact bundle by the surface wrappings.

Such wrapped yarns can be made by drafting substantially zero twist strands of discontinuous fibers to form loose fibers, forwarding the fibers in an air stream, continuously feeding at least two continuous multifiber core elements to converge with the air-borne discontinuous fibers and pass through a false-twisting device to false twist the core elements together to cause twist to back up and combine the discontinuous fibers with the core elements and then reverse-twisting the discontinuous fibers tightly about the core elements by twist transference from the untwisting of the core elements as described in Belgian Patent 669,797, granted Sept. 30, 1965.

The filaments and fibers making up the continuous core elements and discontinuous fibers may be composed of the same or different compositions of natural, regenerated or synthetic fibers or mixtures thereof. Typical examples include cotton, bast, rayon, polyamides, polyesters, acrylonitrile polymers and copolymers, polyethylenes, poly propylenes, polyolefins, and the like.

Preferably the fibers in the continuous core elements will bear a cordage finish in addition to any finish that is applied in the manufacture of the fibers. A particularly suitable group of cordage finishes are described in US. Patent 3,155,537 to Patterson et al.

Typically a yarn of industrial grade continuous filaments such as an 1100 total denier yarn having 192 filaments with essentially zero twist is used as a core element. From two to forty-two or more ends of yarn are combined with staple fibers in an amount of from about 2 to of the total weight of the yarn to produce the wrapped yarn. The wrapped yarns may have total denier of from 1,000 to 100,000 or more with a twist differential between core and surface wrapping of from 2 to about 20 or more turns per inch.

In manufacturing one-half inch diameter rope, for example, several ends of the above wrapped yarn are formed into a rope strand by twisting (typically 8 to 10 turns per foot in the S directionhereinafter S). The wrapped yarns are usually twisted about a core of one or more wrapped yarns in order to provide a strand of round cross-section. In some instances, it may be desirable to feed to the strand-forming step a mixture of several ends of wrapped feed yarn, some of which have the twist differential between the core and wrappings as S twist and some of which have Z twist.

The strands (typically 3 or 4) are then twisted together in a Z direction approximatey seven turns per foot in the rope laying step. Alternatively, the wrapped yarns can be twisted in a Z direction and the resulting rope strands then twisted in an S direction to lay the rope. The amount of twist in the rope-laying step will vary depending on the rope diameter and upon the type of enduse intended for the final rope product. For large diameter ropes and cordage, such as mooring lines, hausers, towing lines, and the like, normally only a few turns per foot are applied. Obviously, any denier wrapped feed yarn may be selected, and the denier of the strand and rope product may vary depending upon the number of ends selected for particular end-uses.

One of the chief advantages of this invention is the provision of a process for making rope using fewer manufacturing steps, which reduces the cost of rope manufacture in addition to producing a superior rope. Not only are the number of rope-making steps reduced in the present process, but another advantage exists in that lower twist levels will be present in the final rope. In conventional rope manufacture, high levels of twist are inserted into the rope yarns and cords to provide abrasion and snag resistance and to produce firmness in the rope. The introduction of twist into the rope, however, increases the degree of elongation of the rope due to the coil-spring effect. The ropes of this invention, however, have a combination of high abrasion and snag resistance, a low degree of elongation, higher strength to weight ratio, better gripping with less lippage on a capstan, and superior aesthetics and stability. Therefore, a rope is produced in this invention which has a combination of improved properties not attainable in a single rope made heretofore.

Applicant believes, without intending to be bound by any theory, that the principle that accounts for the superior rope properties is in part due to the unique nature of the wrapped yarn. Since the core elements of this yarn are zero twist the yarn is balanced and has no coil sping effect. This is permitted by the staple wrapping which takes the place of twist in providing abrasion and snag resistance.

The effectiveness of the staple wrapping is surprising considering the superiority of ropes made with wrapped yarns over ropes made from equivalent synthetic con tinuous filaments by the known alternate process of singles twisting the filaments to form a rope yarn, thermally stabilizing the twist to achieve a balanced rope yarn, twisting several balanced rope yarns into a strand and twisting several strands into a rope. Ropes made with wrapped yarns are superior to ropes made with thermally stabilized rope yarns in that the ropes made with wrapped yarns have superior hockle resistance. The term hockle is commonly used in the cordage industry to describe what happens when a rope made from several strands twisted together is worked to partially untwist the strands, and at least one of these strands loops back upon itself. Every rope will hockle if worked sufiiciently, but some resist more than others. Ropes made with wrapped yarns have equivalent hockle resistance as conventional ropes made as described in the Himmelfarb et al. patent and both are superior to ropes made from thermally sta bilized rope yarns as described above.

The present invention is useful for reducing the cost of manufacturing twisted structures and improving the properties of a variety of twisted structures useful in a number of applications. For example, twisted structures of wrapped yarns may be prepared for use as such or in ropes, braided ropes, nautical ropes, hausers, mountaineering ropes, cords, fire hose (both warp and filling), wrapped hose, filters, twine, conveyors belts, V- belts, tire cord, webbings and tapes, wrapped insulation, rubber coated products, sewing thread, nets, fishing lines, coated fabrics, industrial hose reinforcement, industrial belts, wicking, upholstery, carpets, industrial and household cords and twines, including twine for machine tying of magazines, mail and the like, baler twine and hand twine,

specialty structures for use as an effect thread of cord in styling different types of fabrics and the like. The plytwisted structures may also be used in making different types of woven, knitted, non-Woven, and tufted fabrics, in the industrial textile field, the home-furnishing textile field and the apparel textile field.

For some purposes it may be desirable to apply some twist to the wrapped yarns before plying into other structures.

Examples.The following examples illustrate specific embodiments of this invention Without intending to limit the scope of the invention.

EXAMPLE I The starting material for wrapped yarn A is a polyester industrial type continuous filament yarn of 1100 total denier (192 filaments) with essentially no twist bearing a composition of 87.5 parts of #50 white mineral oil, 2.0 parts of aluminum monopalmitate, 10.0 parts of oxidized polyethylene and 0.5 part of an antioxidant as a cord finish and a sliver of polyester staple fibers of 3 denier per filament (d.p.f.) and about 3.5 inches cut length. Using the process of Belgian Patent 669,797 the sliver is conducted through a drawing frame and delivered at about 51 yards per minute (y.p.m.) [47 meters per minute (m.p.m.)] to a tube under vacuum into which are conducted radially 6 ends of the industrial yarn at about 106 y.p.m. (97 m.p.m.). The yarn and the entangled staple are conducted through an aspirating torque air jet which false twists the yarns and the product wound up at about 101 y.p.m. (92 m.p.m.). The wrapped yarn product comprising continuous filaments as core elements and 10% staple as surface wrapping has a total denier of 7296, a breaking strength of 126 pounds (58 kilograms) and an elongation at the break of 12.2%.

A strand having 9.5 turns per foot (t.p.f.) [31 turns per meter (t.p.m.)] in the S direction and containing 32 ends of the wrapped yarn (A) is made by twisting 10 groups (each group having 3 wrapped yarns) about a core of 2 wrapped yarns. Three ends of the strand are then twisted into a rope (A) having 7.6 t.p.f. (25 t.p.m.) in the Z direction.

For comparison with above rope (A), rope (B) is made by the conventional process. Five ends of the same industrial yarn are twisted into a rope yarn having 43 t.p.f. S (141 t.p.m.). Three ends of the rope yarn are twisted into a rope cord having 22 t.p.f. Z (82 t.p.m.). A strand having 12 t.p.f. S (39 t.p.m.) is made by twisting l2 cords about a core of 3 cords. Three ends of the strand are then twisted together to give rope (B) having 8.5 t.p.f. Z (28 t.p.m.).

The properties of the 2 ropes are shown in Table I where the higher breaking length and lower break elongation of the rope of this invention (item 1A) are apparent over that of the rope produced in accordance with the prior art (item 1B).

The twist differential between the continuous core elements of the wrapped yarn and the staple fiber Wrappings is about 6 to 7 turns per inch.

EXAMPLE II The starting material for the wrapped yarn A is a polyamide industrial type continuous filament yarn of 840 denier filaments) with essentially no twist bearing a cord finish having the following composition:

7.90 parts of a hard, partially oxidized microcrystalline wax;

7.90 parts of a soft paraffin wax;

7.46 parts of an ether of a mol of stearyl alcohol and a mol of polyoxyethylene glycol containing 10 ethylene oxide units;

2.64 parts of a mixture of mono-, diand tri-esters of phosphoric acid with an ether of oleyl alcohol and polyoxyethylene glycol with 7 ethylene oxide units;

2.93 parts of an aqueous emulsion of an acrylic polymer containing about 46% solids;

0.45 part of potassium hydroxide; and

70.0 parts of water;

and a sliver of the polyester staple of Example I.

Following the general procedure of Example I, 17 ends of the polyamide yarn (in groups of twos and threes) are fed into the tube carrying the air stream of staple fibers at 6 point radially spaced around the axis of the tube, false twisted by an air jet and the wrapped yarn Wound up. The wrapped yarn comprising 92.8% by weight of continuous filaments in the core and 7.2% staple fiber as a surface Wrapping has a total denier of 16,289, a breaking strength of 252 pounds (115 kilograms) and an elongation at the break of 19.2%.

A strand having 9.5 t.p.f. S (31 t.p.m.) is made by twisting of the above wrapped yarns around a core of 3 wrapped yarns. Three strands are then twisted together in the opposite direction (Z) to give rope A having 7.6 t.p.f. Z t.p.m.).

For comparison rope (B) is made by the conventional process. Six ends of the same polyamide yarn (840 denier) are twisted into a rope yarn having 43 t.p.f. S (141 t.p.m.). Three ends of the rope yarn are then twisted together to give a cord with 22 t.p.f. Z (72 t.p.m.). A strand having 12 t.p.f. S (39 t.p.m.) is made by twisting 10 cords about a core of 3 cords. The final rope (B) having 8.5 t.p.f. Z (28 t.p.m.) is made by twisting 3 rope strands together.

Properties of the 2 ropes are shown in Table I as Examples 2A and 2B. The superior break length of the product of this invention (2A) is apparent.

The twist differential between the continuous core elements of the wrapped yarn and the fiber wrappings is estimated to be between 3 to 5 turns per inch.

TABLE I Example 1A 13 2A 213 Total ends 1,100 denier yarn 576 675 Total ends 840 denier yarn 663 702 (1) Weight/100 feet, pounds 6. 7 7. 9 6. 0 6. 4

(Weight/100 meters,

kilograms) (10) (11. 7) (8. 9) (9. 5)

(2) Break Strength:

Pounds 6, 893 7, 658 7, 808 7, 800

(Kilograrns) (3, 120) (3, 470) (3, 540) (3, 540) (3) Break length Feet 103, 000 97, 000 130, 000 122, 000

(Meters) (31, 600) (29, 600) (39, 800) (37, 200) Break elongation, percent. 28.8 34. 0 47. 5

(1) The weight per length value is determined under a tension of 50 pounds (22.6 kilograms) for the 0.5 inch (1.2 cm.) diameter ropes.

(2) Breaking strength is determined with an Instron tester using eyesplices in each end of the sample and captan clamps.

(3) The break length is derived from the values for weight/length and the break strength (reciprocal of weight/length times break strength).

Since many different embodiments of the invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited by the specific illustrations except to the extent defined in the following claims.

What is claimed is:

1. The process of forming a stranded rope structure which comprises twisting in one direction a plurality of substantially zero twist wrapped .yarns to form a rope strand, said yarn having from 2% to about 20% by weight of staple fiber wrapping and having a twist differential between continuous core elements and said wrappings within the range of about 2 to about 20 turns per inch; and then twisting a plurality of said rope strands in an opposite direction to form the rope; said wrapped yarn being characterized as comprising a core composed of at least two continuous integral core elements of bundles of continuous filament textile fibers and surface wrappings composed of textile fiber staple, the surface fibers being tightly twisted about the core with portions of fibers locked into place in the core with the core fibers being relatively straight and held together as a compact bundle by the surface wrappings.

2. The process as in claim 1 wherein the wrapped yarn has a denier within the range of about 2,000 to about 100,000.

3. The process as in claim 1 wherein said wrapped yarns are twisted from 2 to 15 turns per foot to form the strands and the strands are twisted from 1 to 12 turns per foot to form the rope.

4. A stranded rope structure which comprises a plurality of substantially zero twist wrapped yarns twisted in one direction to form a rope strand, said yarn having from 2% to about 20% by weight of staple fiber wrapping and having a twist differential between continuous core elements and said wrappings within the range of about 2 to about 20 turns per inch; said strands being twisted in an opposite direction to form the rope; said wrapped yarn being characterized as comprising a core composed of at least two continuous integral core elements of bundles of continuous filament textile fibers and surface wrappings composed of textile fiber staple, the surface fibers being tightly twisted about the core with portion of fibers locked into place in the core with the core fibers being relatively straight and held together as a compact bundle by the surface wrappings.

5. The .rope as in claim 4 wherein the wrapped yarn has a denier within the range of about 2,000 to about 100,000.

6. The rope as in claim 4 wherein said wrapped yarns are twisted from 2 to 15 turns per foot to form the strands and the strands are twisted from 1 to 12 turns per foot to form the rope.

7. The rope as in claim 4 wherein said yarns are of a polyester.

8. The rope as in claim 4 wherein said yarns are of a polyamide.

References Cited UNITED STATES PATENTS 3,201,930 8/1965 Stirling 57144 3,336,743 8/1967 Marshall 57-144 3,365,872 1/1968 Field 57140 XR JOHN PETRAKES, Primary Examiner. 

